Abstract : The paper presents the evaluation of a regional energy efficiency programme in France dedicated to space heating in the residential sector. The large French energy company EDF provides refurbishment advice and financial incentives to the end-users as well as training courses and certification to local installation contractors and building firms. Due to the pilot character of the programme the evaluation is particularly important, both in terms of saved energy and programme costs. Such data were monitored right from the beginning of the programme. In this study, heat pumps for space heating that replace inefficient fossil fuel boilers are analyzed. A billing analysis with temperature normalisation is used to calculate the savings attributed to the programme. Around 90 households were interviewed regarding their individual energy consumption and building as well as household characteristics. Actual data of installation and equipment costs as well as financial incentive payments to customers are provided by EDF. The cost-effectiveness is determined from the perspective of the participant and society as well as EDF. All cost and benefit components are calculated in Euro/kWh, which allows a direct comparison of levelized costs of conserved energy with the avoidable costs of the energy supply system. Results are also expressed in benefit-cost ratios. Critical parameters like the future energy and carbon price development are considered to achieve the most accurate and reliable estimates. Uncertainties are assessed using Monte Carlo simulations. Energy savings and cost distributions are crossed with random probability distributions of the underlying assumption parameters such as the growth rates of future energy and carbon prices. The results indicate how reliable the cost-effectiveness of the programme is from each of the three evaluated perspectives.